Currently, a large selection of biochip detection apparatuses is provided in the industry, and a flow cytometer is one type of biochip detection apparatus. Flow cytometry is technique used for identifying and separating cells suspended in a stream of fluid. This technique is also applicable to detect physical properties of cells.
When a flow cytometer is used for cell separation and identification, a charge is selectively applied to the cells. After passing through an electric field, these cells deviate from the original path and flow out from a different exit. Accordingly, the cells can be accurately and rapidly separated from a cell mixture.
When a flow cytometer, which includes a plurality of light sources and optical detectors, is used for detecting the physical properties of cells, as cells suspended in the stream of fluid pass through a light beam, light is scattered. Further, the cells may be excited into emitting a fluorescent light at a frequency lower than that of the light source.
FIG. 1 is a schematic diagram of a conventional biochip. Referring to FIG. 1, after placing a fluid containing the to-be-detected cells inside the biochip, the user places a probe, serving as an electrode, to directly contact the fluid on the biochip 10 and to apply a bias to cause the fluid containing to-be-detected cells to flow in the micro-fluid channel. The flow cytometer then emits a detection light beam, causing each cell suspended in the fluid passing through the detection light beam to generate a fluorescent reaction. The changes of the scattered light and the fluorescent reaction are recorded by the light detector 20. According to the detection result of the light detector 20, the physical and the chemical properties of the cells are calculated. However, prior to performing the next detection, the probe 30 used to directly contact the fluid containing the to-be-detected cells must be thoroughly cleaned to avoid contaminating the next samples.